Conflicts between millis() and tone()

[kr4fty]

Hi everyone, I'm working with a stm32F103 mcu. It turns out that I use millis() to refresh the reading of data through analogRead. The thing is that I use reading from a button, which would make me activate a process and also produce a tone, through tone(). I notice that when I use millis it stops at that moment and continues once the tone() function has finished, as if tone did not take any time.

The problem comes because both millis() and tone() use the same timer?

my code:

#include <Arduino.h>

#define LED LED_BUILTIN

void setup()
{
    pinMode(LED, OUTPUT);
    digitalWrite(LED, LOW);

    pinMode(BUTTON_PIN, INPUT_PULLUP);
    
    Serial.begin(9600);
}

bool isButtonClicked;
unsigned long start, end, x;
void loop()
{
    if(!digitalRead(BUTTON_PIN)){
        delay(25);
        if(digitalRead(BUTTON_PIN))
            isButtonClicked = true;
    }
    if (isButtonClicked){
        isButtonClicked = false;
      
        start = millis();
        tone(BUZZER_PIN, 4000, 40);
        end = millis();
        digitalWrite(LED, LOW);

        Serial.print(end-start);
   }
}

my output:

0
0
0
0

[fpistm]

Hi @kr4fty
There is no issue from my point of view.
HardwareTimer is used for the Tone so you used Hardware ressources.
While millis uses the systick.

So when you do:

        start = millis();
        tone(BUZZER_PIN, 4000, 40);
        end = millis();

Tone simply configure the HardwareTimer and exit immediately. So having 0 is coherent.